Beryllium product and method of making same



United States Patent Cfitice 3,298,829 Patented Jan. 17, 1967 3,298,829BERYLLIUM PRODUCT AND METHOD OF MAKING SAME Charles J. Havel, Allentown,Pa., assignor to The Beryllium. Corporatiomkeading, Pa, a corporation ofDelaware No Drawing. Filed June 18, 1965, Ser. No. 465,167

5 Claims. (Cl. 75-212) Another object of the present invention is toproduce a beryllium metal having superior elastic modulus, highprecision elastic limit, and high tensile strength which will notexperience grain growth during fabrication.

A further object of the instant invention is to set forth a process ofproducing high strength by beryllium alloys wherein the alloy ischaracterized by a beryllide of the alloying metal at the interfacebetween the particles, and surrounding each particle of beryllium powderso as to inhibit grain growth and reinforce the beryllium matriX.

A more specific object of the instant invention is to set fortha processwhereby beryllium powder is coated with a thin coating of a metal whichwill form a beryllide when pressed into shape under heat.

Other objects and advantages of the invention will become more apparentfrom the following detailed description and examples.

it has been found that high strength beryllium metal can be formedwithout sacrificing low bulk density and at the same time havingsuperior elastic modulus, high precision elastic limit, and high tensilestrength by coating beryllium powder with a metal capable of forming aberyllide and subsequently hot-pressing the powders to form the newberyllium metal.

The beryllium powder used is of a size of about 4 to 74 microns, butpreferably in the order of 4 to microns. This powder is coated with ametal capable of forming a beryllide in any suitable manner, such as forexample in the process disclosed in copending application Serial No.442,240, filed March 22, 1965, which is a continuation-in part ofapplication Serial No. 260,857, now abandoned. In practice, coatings ofup to 50 Angstroms have been found suitable. This powder when subjectedto pressure and heat forms a beryllide on the surface of each individualparticle and at the interface between particles which inhibits graingrowth and reinforces the beryllium matrix.

Typical of the metals which form beryllides are chromium, copper,nickel, columbium, molybdenum, cobalt and iron. The pressure can varyfrom 350 pounds per square inch to 2000 pounds per square inch, and thetemperature for pressing may vary between 1900 F. to 2200 F. Thepressure and temperature utilized as well as the duration of pressingmay vary dependent upon the physical characteristics, such as size ofthe shape being produced.

Some typical examples illustrating the compositions, processes andcharacteristics of the beryllium metal are the'following';

Example 1 Nominal 11 micron beryllium powder was vacuum hotpressed at2000" F. and 2000 psi.

The chemistry of both the treated powder and the resultant pressing are:

By Analysis, percent Constituent Treated Powder Hot Pressed BalanceBalance 1 Xray diffraction.

Example I when hot-pressed and tested gave the following properties:

Test Direction 2% Y.S. Peg'ient Nil 1 Tested with cxtensoineter,premature notch failure, modulus equals 55.6)(10 and 52BX10respectively.

2 Not determined due to gage slippage.

3 Tested without extensometer.

L Longitudinal specimen.

'1 Transverse specimen.

Some other examples showing beryllium metals in which the powders werecoated with chromium are the follow ing:

TAB LE I [Typical chemistry of Be'Cr] Constituent Example No. II ExampleNo. III

. 26S 438 113 127 027 034 095 L 001 015 L 001 210 235 027 039 Balanceliala nce Note-L indicates less than.

TABLE 11 [Mechanical properties of Be-Cr (as pressed)] UTS (K s.i.) 1niieroinch 2 microinches PEL (p.s.i.) PEL (p.s.i.)

No. I 104. 0 26, 500 29. 750 103. 0 22, 37. 700

Example I was subjected to solution annealing after pressing, and gavethe following results.

TABLE III [Property response of Example I to solution annealing][Hardness response to solution annealingair cooling] Tem- Hardness RBExample I perature, Time Sample No. F.

Before After Change 2, 175 1 101 100 2, 175 2 102 97 2, 175 4 101 95 2,175 8 100 93 2, 175 16 102 89 2, 175 32 101 88 2, 200 l 101 97 2, 200 299 94 2, 200 4 101 94 2, 200 8 101 90 ll 2, 200 21 104 92 -12 Thefollowing tests were made to show the superior strength of metal-coatedberyllium powder over a typical surface-oxidized beryllium powder:

Example V Composition A.-Nominal 11 micron beryllium powder waschrome-coated and vacuum hot-pressed at 2000 F. and 2000 p.s.i. yieldinga density of 1.876 gr./cc. The powder and hot-pressed chemistries were:

Powder, percent Hot-Pressed,

percent 274 231 130 110 029 040 016 017 031 055 111 095 190 210 BalanceBalance 1 X-ray difiraetion.

Composition B.Ball milled beryllium powder, surface oxidized to aminimum of 4.25% BeO and containing no alloy coating was vacuumhot-pressed at 2000 F. and 2000 p.s.i. yielding a density of 1.892gr./cc. Weighted average powder particle size per Coulter Counter was8.2

The above examples were tested and showed the following results:

TABLE V UTS YS Elongation PEL (p.s.i.) (p.s.i.) (percent) (p.s.i.)

Composition A 104, 000 Nil 22,125 Composition B 61, 900 56, 700 0. 75 7,500

TABLE VI Material Original Grain Grain Size alter Size 220 F.2 hoursComposition A 7 microns 7 Composition B 9 microns 13. 3

Other data substantiating the inhibiting effect of the beryllide film islisted below for Composition A.

Hours at 2175" F. Original Size Final Size Final in Mierons in MieronsHardness-Rn It appears that after sixteen hours, full solutioning of theberyllide occurs, as evidenced by the very slight change in hardnessbetween 16 and 32 hours, and the beryllide has diffused into theberyllium matrix. Once the beryllide has diffused into the matrix, graingrowth occurs. For example, note increase from 7.4 to 12.4 after 32hours at 2175 F.

In view of the foregoing, it is apparent that there is provided a newand improved process for producing heat-treatable beryllium metal ofsuperior mechanical properties without sacrificing the weight advantageof beryllium. As set forth above, the process involves the coating ofberyllium powders with a metal which will form a beryllide on thesurface of each individual particle and at the interface of saidparticles when pressed under heat. This beryllide interface preventsgrain growth of the beryllium metal, and reinforces the beryllium matrixby providing a beryllide network throughout the beryl lium pressing,thus increasing the strength of the beryllium product.

This process provides a beryllium product with high strength, a highprecision elastic limit, and a superior modulus of elasticity. Theprecision elastic limit relates to the dimensional stability of themetal and is equivalent to the amount of stress which will cause onemillionth of an inch permanent deformation.

As stated above, it is within the scope of this invention to utilize anymetal for coating the powders which will form a. beryllide on thesurface of the powders when pressed.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, and since thescope of the invention is defined by the appended claims, all changesthat fall within the metes and bounds of the claims or that form theirfunctional as well as conjointly cooperate equivalents are thereforeintended to be embraced by those claims.

What is claimed is;

1. A method of producing a beryllium product characterized by highstrength comprising, coating beryllium powders of a size of from 4 to 74microns with a metal selected from the group consisting of chromium,copper, nickel, columbium, molybdenum, cobalt and iron, and hot pressingthe coated powders at a pressure of from 350 to 5 6 2000 psi. and at atemperature of from 1900 F. to References Cited by the Examiner 2200 F.to form a beryllium product. UNITED STATES PATENTS 2. The process ofclaim 1, wherein the pressed beryllium product is subsequentlyheat-treated to modify the 3150975 9/1964 Beaver et 75-214 strength ofthe product. 5 FOREIGN PATENTS 3. The process of claim 1, wherein thepowders are 527618 10/1940 Great Britain from 4 to 15 microns.

4. The process of claim 1, wherein the coating has a CARL D QUARFORTHPrimary Examiner.

thickness of 50 Angstrorns or less.

5. The process of claim 2, wherein the pressed beryl- 10 DEWAYNERUTLEDGE, Exammefi lium product is heat-treated at from 2000 F. to 2200F. R, L GRUDZIECKI, Assistant for from 1 to 32 hours.

1. A METHOD OF PRODUCING A BERYLLIUM PRODUCT CHARACTERIZED BY HIGHSTRENGTH COMPRISING, COATING BERYLLIUM POWDERS OF A SIZE OF FROM 4 TO 74MICRONS WITH A METAL SELECTED FROM THE GROUP CONSISTING OF CHROMIUM,COPPER, NICKEL COLUMBIUM, MOLYBDENUM, COBLAT AND IRON, AND HOT PRESSINGTHE COATED POWDERS AT A PRESSURE OF FROM 350 TO 2000 P.S.I. AND AT ATEMPERATURE OF FROM 1900*F. TO 2200*F. TO FORM A BERYLLIUM PRODUCT.